Get top marks when analysing figures, tables and images by avoiding common mistakes that students make
This article contains key vocabulary, a strategy for how to approach questions for success, a multichoice quiz with answers, and a big pack of past paper exam questions
Don’t panic, it’s only a graph
The single best exam tip for graphs and tables exam questions is to start by looking at the graph or chart itself. DO NOT LOOK AT THE QUESTIONS FIRST! This single thing will help you avoid the most common mistakes that students make.
But you also need to know what you’re doing. Which means you’ll need to be confident with these terms:
Background Knowledge / Vocabulary:
Independent Variable: The variable that you purposefully set to different values during the experiment
Dependent Variable: The variable that you measure during the experiment, which is unknown until it is measured
Replicate: Experiment data is often replicated - the same data point is recorded multiple times in the same experiment.
Accuracy / Precision: Accuracy is how close the replicated values are to the correct value, and precision is how close they are to each other. If there is an unknown problem with the experiment, results can be very precise but have very low accuracy.
Range / Standard Deviation: The amount of variation in the data. A large range or standard deviation means that the replicated data had a broad range of results. A small range or standard deviation means they were much more similar in value. Range / Standard deviation is therefore a measure of precision.
Trend: Is the graph going up or down? What’s the general relationship between the dependent and independent variables? When the experimenter increased the independent variable, what happened to the dependent variable?
How to Approach the Question:
1. Look at the graph or chart first!
Too many students look at the question first, get confused or panicky about what it is asking, and form preconceptions about what data they need. This then means they are then unable to look at the data clearly, and miss the information they actually need. Looking at the graph or chart first both makes the data easier to understand, and makes it easier to work out what the question is asking.
Trust me, this is a major factor in student success. If you only take away one thing from this article, always look at the graph or chart first.
But don’t just dive in to the details of the data …
What’s going on here?
2. Understand the format
Don’t waste time looking at the actual dots or numbers until you understand how the data has been presented. Check every aspect methodically. It’s too easy to make assumptions based on previous graph/table formats you have seen - this one might be different!
Look at the headings / axis labels and units. What is the data showing?
Identify the independent variable and the dependent variable. If possible, it’s helpful to label them “IV” and “DV”.
What type of data is shown? Is it averages? Does it include a Range or Standard Deviation?
Graphs: Check the axis labels. Have they plotted rate or time, mass/volume or concentration? Often students assume enzyme graphs have rate on the y axis - but sometimes they don’t!
Tables: Check: is the Independent Variable in the first column? Is the data in each row consistent?
3. Look at the data
Now you understand its context, look at the actual dots or lines or numbers. Check:
Does the Range overwhelm differences in values: Do the range bars or standard deviation bars overlap? If they do, then there is significant overlap between the populations of replicated results that were used to calculated the average values.
Unspecified Ranges: If there are replicates but no range bars or standard deviation has been calculated, how broad does the range look when you compare the replicated data values to their mean?
Trends: What trends can you observe? Then think about what principle of biology is being shown by the the trends.
Now think about what it all actually means:
Values: How would you explain the highest value, the lowest value, the point at which the line crosses the x axis,
Range: How would you explain the largest range? How would you change the method to reduce the spread in the data?
4. Ok - NOW look at the actual questions
Students can get very thrown by the details in questions. For instance, if the question is about an organism or molecule that they have never heard of before (the exam boards do this a lot). This sudden panic makes it hard to think clearly.
Remember - if you have covered all the course material, and the question is about something that looks totally unfamiliar, all the information you need will be in the question. And you already know what the data shows/means, so you can read the question with that in mind.
5. Give the required information
Avoid the common mistakes that lose students marks:
If they say you should use the data, you must either quote it, or show how you have used in in a calculation
Refer to the axis/data labels wherever possible. Don’t say “the graph goes up”, do say “the saturation of haemoglobin increases”
A-Level Biology Past Paper Graphs and Charts Exam Questions:
Got all that? Ok! Here are some questions for you to practice.
And remember - don’t read the questions until after you have made sense of the graph or chart.
This article was written by Dr Jenny Shipway with tips and advice from Tom. Tom has over 26 years experience specialising in A level Biology teaching and tuition, and has guided many students to achieving top grades in the subject.